Week 14 Homework Assignment

1. (a) What is the approximate radius of a ⁶⁴₂₉Cu nucleus? (b) Approximately what is the value of A for a nucleus whose radius is 3.7 x 10^-15m?
2. Calculate the total binding energy and the binding energy per nucleon for ⁶₃Li Use Appendix F.
3. The isotope ²¹⁸₈₄Po can decay by either a or b^- emission. What is the energy release in each case? the mass of ²¹⁸₈₄Po is 218.008965u.
4. ¹²⁴₃₅Cs has a half-life of 30.0s. (a) If we have 7.8mg initially, how many nuclei are present? (b) How many are present 2.0min later? (c) What is the activity at this time? (d) After how much time will the activity drop to less than about 1percent?
5. ⁷₄Be decays with a half-life of about 53d. It is produced in the upper atmosphere, and filters down onto the Earth's surface. If a plant leaf is detected to have 350 decays/s of  ⁷₄Be, how long do we have to wait for the decay rate to drop to 10/s? Estimate the initial mass of  ⁷₄Be on the leaf.